base_gdt_load.c

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/*
 * base_gdt_load.c
 * Modified for use in 15-410 at CMU
 * Zachary Anderson(zra)
 */

/*
 * Copyright (c) 1996-1998 University of Utah and the Flux Group.
 * All rights reserved.
 * 
 * This file is part of the Flux OSKit.  The OSKit is free software, also known
 * as "open source;" you can redistribute it and/or modify it under the terms
 * of the GNU General Public License (GPL), version 2, as published by the Free
 * Software Foundation (FSF).  To explore alternate licensing terms, contact
 * the University of Utah at [e-mail] or [phone].
 * 
 * The OSKit is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GPL for more details.  You should have
 * received a copy of the GPL along with the OSKit; see the file COPYING.  If
 * not, write to the FSF, 59 Temple Place #330, Boston, MA 02111-1307, USA.
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990 Carnegie Mellon University
 * Copyright (c) 1991 IBM Corporation 
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation,
 * and that the name IBM not be used in advertising or publicity 
 * pertaining to distribution of the software without specific, written
 * prior permission.
 * 
 * CARNEGIE MELLON AND IBM ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON AND IBM DISCLAIM ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  [e-mail]
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */

#include <x86/proc_reg.h>
#include <x86/seg.h>
#include <base_vm.h>
#include <x86/base_gdt.h>

void base_gdt_load(void)
{
	struct pseudo_descriptor pdesc;

	/* Create a pseudo-descriptor describing the GDT.  */
	pdesc.limit = sizeof(base_gdt) - 1;
	pdesc.linear_base = (unsigned int)&base_gdt;

	/* Load it into the CPU.  */
	set_gdt(&pdesc);

	/*
	 * Reload all the segment registers from the new GDT.
	 */
	asm volatile("\
		ljmp	%0,$1f;\
	1:\
	" : : "i" (KERNEL_CS));
	set_ds(KERNEL_DS);
	set_es(KERNEL_DS);
	set_ss(KERNEL_DS);

	/*
	 * Clear out the FS and GS registers by default,
	 * since they're not needed for normal execution of GCC code.
	 */
	set_fs(0);
	set_gs(0);
}